It is known to prepare dichlorohydrin by reacting in a reaction zone allyl chloride, water and chlorine in dilute aqueous phase, see e.g., U.S. Pat. No. 2,714,121 and U.S. Pat. No. 2,714,123, incorporated herein by reference. The term "dichlorohydrin" herein designates the isomers 2,3 dichloro-1-propanol and 1,3 dichloro-1-propanol. The reaction zone effluent may be worked up in various ways to recover the dichlorohydrin therefrom, or may be processed further in an integrated process to convert the chlorohydrins to derivatives such as epichlorohydrin and/or glycerine.
It is known e.g., from Belgian Pat. Nos. 614,890 and 614,891 that dichlorohydrin may be extracted from aqueous solution with organic solvents such as phosphate esters of aliphatic monohydric alcohols containing more than four carbon atoms, aryl phosphates, and liquid aliphatic alcohols and liquid ketones having 8 to 18 carbon atoms per molecule.
From Japanese Pat. No. 74,00369 it is known that the product mixture from the reaction of a lower olefin, chlorine and water can be electrodialyzed to remove the by-product ions of hydrogen and chlorine, and the ion-depleted chlorohydrin solution circulated to the reaction zone enabling the production of a concentrated aqueous chlorohydrin solution.
U.S. Pat. No. 3,909,382 discloses recovering acid values such as hydrochloric acid formed during olefin chlorohydrination by series flow through a plurality of electrodialysis stages to upgrade the acid to higher concentration.
One disadvantage of the known processes is that substantial amounts of water are used in the reaction zone of the process to reduce formation of undesired by-products, which by-products reduce the overall efficiency of the process and may complicate purification procedures of the desired product. Such conventional processes result in an aqueous effluent stream which contains minor amounts of organic impurities diluted in a substantial amount of water. Such effluent requires energy intensive treatment to reduce the amount of organic materials to levels acceptable to be passed to receiving bodies of water such as rivers, lakes and the like. Considerable savings could be effected if the amount of water to be treated could be significantly reduced.